Your First IUI: What the Day Looks Like, Success Rate

It is the night before your first IUI, or the morning of, and you are reading this somewhere between the kitchen table and the clinic parking lot. You want a minute-by-minute version of what is going to happen, and you want an honest answer to the question most people will not give you straight: what is the success rate for IUI first try? Roughly 10 to 15 percent under 35, not the 40 percent some forum threads imply. That is the headline. The rest of this post is the day itself.

The procedure takes about five minutes. Everything else is logistics, paperwork, and waiting. Knowing the order of the day in advance is the single biggest thing that brings the heart rate down when you walk in.

The 24-hour timeline

If your clinic uses a trigger shot, you will give yourself Ovidrel (recombinant hCG, 250 micrograms subcutaneously) or a generic hCG preparation roughly 36 hours before your IUI. The shot tells the lead follicle to release its egg on a predictable schedule, so the insemination can be timed precisely instead of guessed from your luteinising hormone (LH) surge.

If you are in an unmedicated or "natural" cycle, you skip the trigger and use ovulation predictor kit (OPK) tests instead. A clearly positive OPK in the morning usually means the IUI will be scheduled for the next day. A late-evening positive sometimes means same-day or next-morning, depending on clinic policy.

On the morning of the procedure, drink water but do not over-hydrate. A partially full bladder helps tilt the uterus into a position that makes the catheter pass easier; an aggressively full bladder is uncomfortable and not required. Eat something light. Vasovagal episodes, the dizzy, sweaty, low-blood-pressure response some people get during pelvic exams, are more common on an empty stomach.

Your partner produces a fresh sample at home or in the clinic about one to two hours before the procedure. Frozen donor sperm is thawed in the lab the morning of. From the moment the sample arrives at the lab to the moment it goes back into your uterus, you are usually waiting for the wash to finish. That is the longest part of the day.

The sperm wash, in one paragraph

The lab uses either density gradient centrifugation or a swim-up technique to separate the most motile sperm from seminal fluid, dead sperm, white blood cells, and debris. The output is a small volume, typically 0.3 to 0.5 millilitres, of concentrated washed sperm suspended in culture medium. The key number is the post-wash total motile count (TMC), which is the total number of forward-moving sperm in the prepared sample. Most clinics want a post-wash TMC above roughly 5 to 10 million for IUI to be worthwhile; below that range, the per-cycle pregnancy rates drop sharply and the conversation often shifts toward IVF. The full threshold discussion lives in IUI sperm count requirements.

Ask for your post-wash TMC before you leave the clinic. Write it down. It is the most useful single number in the cycle and you will want it for the cycle two conversation.

The procedure, step by step

You change into a gown from the waist down, lie on the exam table, and put your feet in stirrups the way you would for a Pap smear or a routine pelvic exam.

A speculum is placed in the vagina to visualise the cervix. Some clinicians wipe the cervix with sterile culture medium to clear away mucus that could interfere with the catheter pass. A thin, flexible catheter, usually around two millimetres in diameter, is threaded through the cervical canal into the uterine cavity. Most people feel pressure during this step. A small minority feel a sharper cramp; this passes within seconds.

The washed sperm sample is injected slowly through the catheter over about 30 to 60 seconds. Many people feel a brief uterine cramp during the injection itself. The catheter and speculum are then removed. You lie flat for five to fifteen minutes. The randomised trial by Custers and colleagues in BMJ found no improvement in pregnancy rates from immobilisation after IUI compared with immediate mobilisation. The Saleh trial in Fertility and Sterility came to a similar conclusion.²,⁴ Most clinics still ask for a short rest period because it costs nothing and reassures patients, but the data is genuinely weak. Once you stand up, the sperm does not fall out. It was placed past the cervix.

Most patients walk out without assistance. No recovery room. No driver required. If you have a vasovagal response, the clinic is prepared for it and will keep you a little longer until it passes.

What to bring and wear

A short list, because the day is otherwise full of variables.

• Comfortable clothing from the waist down. Leggings, loose trousers, or a skirt are easier than jeans.
• A pad for after. Light pink or brown spotting from the catheter is common for a day or so. Skip tampons for 24 hours.
• Water and a small snack for the post-procedure window.
• Insurance card, photo ID, and a payment method. Some clinics collect at time of service.
• If you want your partner in the room, ask in advance. Most clinics allow it. The partner-during-IUI-day question comes up often enough that it has its own post here.

Single versus double insemination

Most clinics do a single IUI timed roughly 24 to 36 hours after the trigger shot or the LH surge. Some offer double IUI, with two inseminations spaced about 12 hours apart in the same cycle. The Cochrane analysis of synchronised approaches by Cantineau and colleagues found no clinically meaningful benefit to double over single IUI for most diagnoses.⁴ There is a narrow case for double IUI in severe male-factor cycles, but most patients do not need it and most clinics no longer recommend it as routine. If double IUI is suggested for your cycle, ask why specifically.

The same caveat applies to many "add-on" practices around IUI. The published evidence rarely supports the marketing.

What is the success rate for IUI first try, honestly

The question "what is the success rate for IUI first try" gets answered very differently depending on who is doing the answering. Here are the numbers I quote in clinic, drawn from large observational series including the Bahadur 2020 BMJ Open analysis of 30,669 UK IUI cycles, and consistent with the ASRM and NICE summaries.¹,³,⁵

• Under 35, per-cycle live birth on a medicated IUI: roughly 10 to 15 percent.
• 35 to 37: roughly 8 to 12 percent.
• 38 to 40: roughly 5 to 8 percent.
• 41 and over: usually under 4 percent, and most reproductive endocrinologists will have a conversation with you about IVF instead.

A few things are worth knowing about how to read those numbers. First, "per cycle" means the chance that this one cycle produces a live birth, not the chance you ever have a baby through IUI. The cumulative live birth across three to four cycles is meaningfully higher than any single cycle, which is why IUI is designed as a repeated treatment. Second, the cycles are roughly independent through cycle three or four. A negative cycle one does not lower your odds for cycle two in any clinically meaningful way. Third, the second IUI success rate and the third IUI success rate are not very different from the first. The larger drop happens after about four cycles. By then, whatever was limiting the cycle becomes the limiting factor for the next cycle too.

If you walked into clinic with two mature follicles at trigger, your per-cycle odds are slightly higher than with one, particularly in unexplained infertility. The trade-off is a slightly higher multiple-pregnancy rate, mostly twins. The "2 follicles IUI success rate" framing online sometimes implies a doubling of odds; the real bump is modest, roughly 1.3 to 1.5 times, depending on the diagnosis.

After the procedure

You will have light cramping for the rest of the day, similar to mild period cramps. Pink or brown spotting for one to two days is normal and comes from the catheter brushing the cervix, not from the procedure failing. There is no requirement for bed rest beyond the short rest at the clinic. You can drive yourself home and return to work that afternoon if you want to.

Walking, normal household activity, and light exercise are all fine. Sex after IUI is permitted by most clinics after 24 to 48 hours and does not clearly help or hurt cycle outcomes.

The deeper post-procedure guidance lives in After Your IUI: What to Do and What to Avoid, including how to think about the symptom-spotting trap in the two weeks before the beta hCG test.

Common worries: what is normal, what is a red flag

A few questions almost always come up in the cycle one follow-up call.

• Spotting for a day or two: normal. The catheter touched the cervix.
• Cramping for a few hours: normal. The uterus is responding to a small volume of fluid.
• Feeling like the sample is "leaking out": not what is happening. The sample was placed past the cervix, and what you may feel later is residual cervical mucus or a small amount of seminal fluid that was not part of the wash, washing back out.
• Heavy bleeding (soaking a pad in an hour), a fever above 100.4 degrees Fahrenheit (38 Celsius), or severe one-sided pelvic pain: call the clinic. Pelvic infection after IUI is uncommon but it does happen, and one-sided pain in the days after needs to be ruled out for ovarian torsion or, rarely, hyperstimulation.
• You forgot to drink water: fine. Tell the nurse, and they will work with what they have. The full-bladder advice is a soft preference, not a requirement.

What to ask before you leave

The five questions that pay off for cycle two, written down on your phone before you go in:

1. What was the post-wash total motile count for this cycle? Write the number down.
2. How many mature follicles were seen at the trigger scan, and at what sizes?
3. What was the endometrial thickness at trigger? Most clinics target above 7 millimetres.
4. When is the beta hCG blood test scheduled? Typically 14 to 16 days post-IUI.
5. If progesterone support is prescribed, when do I start it, in what form, and for how long?

The first cycle is when most patients are absorbing too much at once to remember details. The answers shape every conversation about cycle two and beyond. What is the success rate for IUI first try is, for most people, the wrong frame; the right frame is what is the cumulative rate across the cycles you and your RE have actually planned for.

What's next

• If you are home from the procedure and managing the wait → After Your IUI: What to Do and What to Avoid
• If pain is your main worry → Does IUI Hurt: What to Expect Physically
• If you are weighing cost before booking → IUI Cost: Per Cycle, With and Without Insurance
• If the cycle did not work → Failed IUI: What to Do Next
• If you want to step back to the pillar → IUI Explained

Sources

1. Practice Committee of the American Society for Reproductive Medicine. Performing the embryo transfer: a guideline. Fertility and Sterility 2017;107(4):882-896. https://www.asrm.org/practice-guidance/practice-committee-documents/
2. Custers IM, Flierman PA, Maas P, et al. Immobilisation versus immediate mobilisation after intrauterine insemination: randomised controlled trial. BMJ 2009;339:b4080. doi:10.1136/bmj.b4080. https://doi.org/10.1136/bmj.b4080
3. Bahadur G, Homburg R, Bosmans JE, et al. Observational retrospective study of UK national success, risks and costs for 319,105 IVF/ICSI and 30,669 IUI treatment cycles. BMJ Open 2020;10(3):e034566. doi:10.1136/bmjopen-2019-034566. https://doi.org/10.1136/bmjopen-2019-034566
4. Cantineau AEP, Janssen MJ, Cohlen BJ, Allersma T. Synchronised approach for intrauterine insemination in subfertile couples. Cochrane Database of Systematic Reviews 2014;(12):CD006942. doi:10.1002/14651858.CD006942.pub3. https://doi.org/10.1002/14651858.CD006942.pub3
5. National Institute for Health and Care Excellence. Fertility problems: assessment and treatment. NICE Guideline NG156. Originally CG156, updated 2017. https://www.nice.org.uk/guidance/ng156
6. Practice Committee of the American Society for Reproductive Medicine. Optimizing natural fertility: a committee opinion. Fertility and Sterility 2022;117(1):53-63. doi:10.1016/j.fertnstert.2021.10.007. https://doi.org/10.1016/j.fertnstert.2021.10.007